1. Field of the Invention
The present invention relates to an improvement in the number-entry keys of numerical keyboards used in electronic calculators and other number input devices with the addition of three structure keys, one swap control key and a method to enter numbers in a way consistent with the oral expression of the number.
2. Description of the Prior Art
Numerical keyboards used in electronic calculators have two categories of keys: number-entry keys and function keys. Number-entry keys are used to enter a number into an input register during a number input operation. Function keys are used to end the number input operation and start a sequence of procedures to process the number stored in the input register.
All numerical keyboards have a basic set of 10 number-entry keys corresponding to the "0" to "9" digit keys. Most numerical keyboards also have a decimal point key ".". Examples of other number-entry keys are the sign key ".+-." used to change the sign of the number, the delete key "del" used to delete the last digit or decimal point entered in the number, and the exponential key "EE" used to start entering the power of ten of a number expressed in scientific notation.
Keyboards of some specialized electronic calculators also have multi-zero number-entry keys "00" and "000" to simplify the number input operation by depressing them once instead of depressing the digit key several times.
All numerical keyboards used in electronic calculators have a set of seven function keys: "+", "-", ".times.", "/", "=", "CE", and "C" to perform the four arithmetic operations by using the number stored in the input register and a number previously stored in an accumulator register as operands, display the result in the display device, clear the contents of the input register or clear the contents of all registers; conventional calculators also have memory function keys "M+", "M-", "MR", and "MC" to perform operations on the memory register; specialized calculators have many other function keys to perform more complex operations including the capability to program the sequence of operations to be performed on the input register number and/or other registers included in the device.
Another example of function keys are the stop "*" and enter "#" keys used in telephone keyboards to indicate the end of a number input operation used to enter an extension or pin number.
As described above, most of the enhancements and special features on electronic calculators and other number input devices are related with the function keys. The conventional number-entry keys and number input procedure are always the same even in most advanced calculators and number input devices. A number is entered by depressing a sequence of digit keys and a decimal point key (if required) until a function key is depressed. An enhancement to the conventional number input procedure is described in U.S. Pat. No. 3,764,791 to Kashio (1973) where depressing a multi-zero number-entry key also generates a carry signal that ends one number input operation and starts a new data-entry operation until a function key is depressed; at this point the number input procedure is ended and the function is performed sequentially on all the numbers entered during the number input procedure. Nevertheless all number input procedures heretofore known have several disadvantages:
(a) as shown in the Appendix included at the end of this specification, numbers are structured entities whose structures are closely related with the way the number is expressed orally; conventional number input procedures require the number to be converted by a mental operation into a decimal numeral (string of single digits) before the number input procedure can be started; PA1 (b) numbers with simple structures, for example, one million five, require depressing many times the digit number-entry keys, for example, 1000005; PA1 (c) conventional number input procedures are not consistent with the way numbers are orally expressed and, therefore, with the way the mind conceives numbers; this inconsistency increases the chances of data-entry errors; PA1 (d) enhanced conventional number input procedures based on the use of multi-zero keys are limited to avoid depressing the "0" digit key several times when entering numbers representing consecutive orders, for example, 1000 or 500; this holds true even in cases where the multi-zero key generates a carry signal to end a partial number input operation. PA1 (a) to provide a way to convert the verbal expression of a number into a decimal numeral as part of the number input procedure; PA1 (b) to reduce, in many instances, the number of keystrokes required to enter a number, for example, the number one million five can be entered by two keystrokes as opposed to the seven keystrokes required by the conventional and enhanced number input procedures; PA1 (c) to provide a structured number input procedure consistent with the way numbers are orally expressed and, therefore, with the way the mind conceives numbers; PA1 (d) to enhance the functionality of the multi-zero number-entry keys by allowing them to enter number structures rather than just a sequence of zeroes during a data-entry operation. PA1 an extended number-entry key matrix with at least 10 digit keys "0" to "9", one "hundred" structure key "H", one "thousand" structure key "T" one "million" structure key "M" and one swap key ".revreaction."; PA1 a key buffer to store the code generated by depressing a key; PA1 a key decoder to analyze the code stored in the key buffer; PA1 a control unit to control the operation of the memory and other components of the system; PA1 a program RAM to store the sequential instructions to be executed by the control unit in correspondence with the code received from the key decoder; PA1 a set of verbal registers to store the sequence of digits and/or structure codes entered during the same number input operation; PA1 a number register comprising a set of control registers to store the value of the input number and the parameters related with number input operation; this set of control registers may contain a data-entry mode register, a data-entry error register, a level register, a number size register, a dot position register and an input number register; and PA1 a display device to display the number stored in the input register, and the status of the data-entry mode register; optionally, this device could emit a "beep" signal whenever the data-entry error register has an error status. PA1 23M1T2H7 PA1 23M1T207 PA1 23MT2H7 PA1 23MT207 PA1 23M1207.